Field of the Invention
This invention relates to an antifreeze composition. Particularly, it relates to an antifreeze composition composed of a glycol, water, and a corrosion inhibiting agent and used for preventing the cooling water in the liquid-cooling type internal combustion engine from being frozen More particularly, it relates to an antifreeze composition which, as used in a cooling water for an automobile engine, manifests the effect thereof not merely in preventing the cooling water from being frozen but also in enabling the cooling system of the automobile engine to maintain the function of protecting the automobile engine against rusting and corrosion.
Description of the Prior Art
Heretofore, the cooling liquid for the liquid-cooling type internal combustion engine such as, for example, the automobile engine has heretofore used customarily, for the prevention of the phenomenon of freezing during the cold season, an antifreeze which uses an alcohol or a glycol as a main ingredient and additionally incorporates a varying corrosion-inhibiting agent to acquire an ability to prevent freezing and corrosion at the same time.
Examples of the alcohol generally used for this purpose include methyl alcohol, ethyl alcohol, and isopropyl alcohol and examples of the glycol generally adopted include ethylene glycol, propylene glycol, hexylene glycol, and glycerol. They are used either singly or in the form of a combination of two or more members. The antifreeze which uses as its main ingredient monoethylene glycol among other compounds cited above finds popular utility in the cooling liquid for the cooling system in the automobile engine.
In the case of an aqueous monoethylene glycol solution, the effect in preventing the freezing is obtained to -15.5.degree. C. with a concentration of 30% by volume and to -37.0.degree. C. with a concentration of 50% by volume.
Alcohols or glycols are oxidized on contact with air to produce acidic alcohols or oxides of glycols. The formation of such oxides of alcohols or glycols is all the more accelerated at an elevated temperature in the range of 50.degree. to 100.degree. C. These acidic alcohols or glycols promote corrosion of the cooling system in the internal combustion engine, particularly the various metal materials used in the automobile engine. The corrosion of the various metal materials of which the cooling system of the internal combustion engine is made is liable to degrade the thermal conductivity of the cooling system or clog the radiator tube with deposition of the product of corrosion and eventually cause an overheating of the engine.
The antifreeze which uses an alcohol or a glycol as a main ingredient thereof has to incoporate additionally therein a corrosion-inhibiting agent because the alcohol or glycol is devoid of an ability to prevent the corrosion.
The corrosion proofing agent for use in the antifreeze incorporates therein at least one member selected from the group consisting of borax, sodium nitrite, phosphoric acid, silicates, sodium benzoate, sodium salt of mercaptobenzothiazole, benzotriazole, methyl benzotriazole, triethanolamine, diethanolamine, monoethanolamine, triisopropanolamine, diisopropanolamine, monoisopropanolamine, cyclohexyl amine, ethylenediamine, hydrazine, pyridine, and morpholine (U.S. Pat. Nos. 3,046,229; 3,362,910; 3,282,846; 3,046,299; 4,149,985; and 4,333,843). As representatives of these compounds, there can be cited borax, phosphate of triethanolamine, sodium benzoate, sodium nitrite, and sodium silicate. Borax has found popular utility as an effective corrosion proofing agent for engines made of cast iron. In recent years, the general trend toward economization of resources and energies has urged the need of producing automobile parts with lighter materials and has consequently encouraged adoption of aluminum parts In the circumstances, the fact that borax is deficient in a capacity for corrosion proofing aluminum materials has constituted itself a serious problem.
It has been known that when an aqueous ethylene glycol solution incorporating borax therein is used in the cooling system of the automobile engine, this solution corrodes aluminum alloy as a material for a cylinder head and a cylinder block in the engine and the product of the corrosion clogs the radiator.
The phosphate of triethanolamine exhibits an outstanding capacity for corrosion proofing iron and aluminum materials and has found utility as a corrosion proofing agent to take the place of borax. A report has been published which purports that triethanolamine in the presence of a nitrite produces nitrosoamine. It is, therefore, desirable to avoid the occurrence of a nitrite where an amine is being used. The sodium benzoate, when used alone, cannot be expected to manifest a corrosion proofing effect favorably comparable with that of the agents mentioned above.
The sodium silicate is also effective in curbing the corrosion. It has a disadvantage, however, that it is liable to undergo separation by gelation during a protracted storage.
An object of this invention, therefore, is to provide a novel antifreeze composition.
Another object of this invention is to provide an antifreeze composition which manifests an outstanding effect in corrosion proofing metal materials.